Production of filaments, threads, bands, ribbons and the like, from cellulose derivatives



Patented Oct. 13, 1936 PRODUCTION OF FILAMENTS,

THREADS,

BANDS, RIBBONS AND THE LIKE, FROM CELLULOSE DERIVATIVES Arthur Eichengriin, Charlottenburg, Germany,

assignor to Celanese Corporation of America,

a corporation of Delaware N Drawing.

Application February 5, 1929,

Serial No. 337,737. In Great Britain February 2 Claims.

This invention relates to improvements in the production of filaments, threads, bands, ribbons and the like particularly from cellulose derivatives such as esters or ethers, by extruding suit- 5 able solutions of such cellulose derivatives.

For the sake of simplicity theinvention will be first described with reference to the production of artificial silk filaments.

The quality of artificial silk filaments produced is at the present time tested by their fineness (denier) and their strength. In order to produce from a given cellulose derivative, for example a cellulose acetate, the desired fineness, i. e., the desired denier, various measures are resorted to, such as for example variation of the size of the spinning aperture, for example, from 0.09 mm. to 0.05 mm., variation of the pressure with which the solution is extruded through the spinning aperture or variation of the tem- 20 perature of the solution or of the spinning cabinet or finally alteration of the amount of the cellulose derivative in the solution.

It has also been attempted to attain fine filaments by using various different solvents for the 25 cellulose derivatives. Thus for example in my copending application Serial No. 68,707 I have suggested producing artificial silk filaments, 7 threads, bands, ribbons and the like, from a noninflammable, homogeneous solution having a base'of acetone soluble cellulose acetate which has been prepared in the cold by treating said acetate with methylene chloride to which an alcohol or a solvent or a mixture of solvents and a non-solvent for said cellulose acetate or a mixture of two non-solvents which together form a solvent for said cellulose acetate have been added at any suitable stage of said treatment, in

amounts compatible with maintaining the mixture non-inflammable.

I have now found a surprisingly simple method of altering the denier of the filaments produced as aforesaid, whilst using the normal spinning apertures, which method may be employed in substitution of or in addition to other known methods of denier regulation such, as above-described.

The method of the present invention consists in employing as vehicle for the cellulose derivative, a mixture comprising a lower boiling point solvent or latent solvent (suchas acetone or a liquid such as methylene chloride which per se is a non-solvent for said cellulose derivative but nevertheless acts as a solvent therefor in the presence of another liquid) in conjunction with one or more higher boiling point coagulants for said cellulose derivative, (such as alcohol, benzol or water) and regulating the dimensions of the extruded filaments or the like without altering the size of the extrusion apertures by adjusting the relative amounts of the constituents of the vehicle keeping said cellulose derivative in solution whilst using winding speeds above the normal (namely about 75 metres per minute) and co-relating said Winding speeds with the dimensions of the extruded filaments or the like.

Thus for example, in the case of solutions of cellulose acetate in a vehicle comprising methylene chloride as latent solvent such-as described in my co-pending application Serial No. 68,707

above referred to, the invention may be carried out by controlling the ratio which the amounts of alcohol constituting the higher boiling coagulant bear tothe amount of methylene chloride in said vehicle.

In order to facilitate comprehension of the invention the same will hereinafter be more fully explained with reference to the following examples.

In Example 1 of artificial silk filaments by the extrusion of a solution of an acetone-soluble cellulose acetate in methylene chloride containing alcohol in amounts compatible with maintaining the mixture non-inflammable. Said application was directed towards the production of a non-inflammable homogeneous solution of cellulose acetate and no particular attention was paid to the amount or proportion of other liquids added to the methylene chloride provided that the solu-.

tion remained non-inflammable. However, by adjusting, in accordance with th-epresent invention, the amount of the ingredients which together with methylene chloride form the solvent proper for cellulose acetate, it is now possible to reduce the denier of the extruded filament below normal whilst'employing the normal spinning apertures.

The results of certain experiments have been set forth in the following tables.

For the sake of comparison I prepared two solutions containing 15 and 20% by weight of cellulose acetate respectively in acetone and solutions containing 15 and 20% by Weight of cellulose acetate respectively in mixtures of methylene chloride with alcohol in various proportions. These solutions were extruded through spinning apertures of 0.08 mm. diameter whilst keeping the temperatures, pressures and spinning speedsasuniform of my co-pending application Serial No. 68,707 I have described the producti0nj as possible. The denier in each case was measured.

V 157 by 207 by Acetone weight weight Pressure in atmospheres 32 35 Temperature C 50 45 Winding speeds in metres per minute. 50 64. 2 Denier 7. 4 5. 2

Solvent mixture:

85 parts by weight methylene chloride. zgzgg 15 parts by weight alcohol. g

Pressure in atmospheres 32 66 Temperature C 50 45 Winding speeds in metres per minute 50 64 Denier 7. 5 6. 0

III

Solvent mixture:

75 parts by Weight methylene chloride. gg gi 2.832 25 parts by weight alcohol.

Pressure in atmospheres 36 71 Temperature C I 48-54 40 Winding speeds in metres per minute- 95 73 Denier 2. 6-2. 8 3. 8

Solvent mixture: 7 9

70 parts by weight methylene chloride.

- '30 parts by weight alcohol.

Pressure in atmospheres 70 Temperature C 39-41 40 Winding speeds in 113 113 Denier 1. 6-1. 9 3. 3

Solvent mixture: i 7

65 parts by weight methylene chloride. 2332 1? parts by weight alcohol.

Pressure in atmospheres... 25 80 Temperature C 45 45 Winding speeds in metres per 111 ut 160 156 Denier 1. 2 2. 9

From the foregoing tables it will be seen that ordinary solutions of 15 or 20% by weight of acetone-soluble cellulose acetate in acetone respectively give a denier of 7.4 to 5.2, whilst solutions of 15 or 20% by weight'of acetone-soluble cellulose acetate in a mixture of 85 parts of methylene chloride and 15 parts of alcohol, give deniers which are respectively not materially altered, viz. 7.5 and 6 respectively. They also show that when the ratio of alcohol to methylene chloride in the solventmixture is increased the denier is considerably decreased i. e., a much finer thread is obtained, and that the smallest denier or finest thread is obtained when the proportion of alcohol in the solvent mixture is increased to 35%.

The foregoing tables thus demonstrate that the adjustment of the relative proportions of the components forming the vehicle for the cellulose acetate i. e. by'increasing the ratio of alcohol filament at which breakage takes place under the influence of the Weight of the suspended filament alone).

I have hereinbefore described only the use of solutions containing methylene chloride and alcohol, but it is obvious that the invention may also be carried out with solutions of acetonesoluble cellulose acetate in other solvent mixtures containing for example alcohol, benzol and acetone such as those described in my British specifications Nos. 1441/1910 and 18076/1910, and that by adjusting the relative proportions of the components (e; g. alcohol, benzol and acetone) forming the vehicle of such cellulose acetate the denier of the extruded filament can be modified at will.

Similar results can also be obtained with other known solvents and mixtures of solvents and nonsolvents or coagulants for cellulose acetate. Thus for example I may employ solvent mixtures consisting of ethylene chloride and alcohol; ethylene chloride, alcohol and acetone; ethyl acetic acetate and alcohol, ethyl formate and alcohol, and may vary the denier by altering the proportion of alcohol. In fact I may even employ a mixture of acetone and alcohol and vary the ratio of alcohol in the mixture in order to modify the denier.

I have also found that instead of modifying the fineness of the thread by modifying the amount of alcohol I can also influence the fineness of the thread by adding small amounts of water with alcohol or other coagulants.

I have above described the application of my invention, to cellulose acetate, however the invention is also applicable to other cellulose derivatives such as other cellulose esters and ethers and cellulose derivatives having inorganic and organic acid radicles, or mixtures of different aliphatic or aromatic acid radicles. For example, I may use ethylcellulose, benzylcellulose and the like, or

cellulose-propionate or even mixtures of esters and others of aliphatic and aromatic acids.

Similar results can also be obtained with alkyl cellulose acetates or nitro-cellulose acetates or mixtures of any of the aforesaid acetates. M

The present invention enables perfect filaments of unvarying cross-section to be obtained, presumably by virtue of the fact that when employing a vehicle comprising a rapidly evaporating solvent and a less rapidly evaporating non-solvent or coagulant, the solidifying effect of the ning artificial filaments bya stretch-spinning process, very low deniers can'be obtained which are comparable to those obtained in the cuprammonium process.

Whilst I have hereinbefore described the application of the invention only to the production or filaments, it is obvious that the invention can also be applied to the production of threads, bands, ribbons and the like from cellulose derivatives, and the term filaments used in the claims includes such threads, bands, ribbons and the like. The breaking length of a filament furnishes a reliable indication of the nature of the7-5 bands, ribbons or the like which could be produced by the extrusion of the same solution of cellulose derivative so that it is possible, by varying the ratio of the components of the vehicle, to vary also the properties of the bands, ribbons or the like produced from such solutions of cellulose derivatives.

It is obvious that innumerable variations and modifications may be made without departing from the spirit or scope of the invention as defined in the appended claims.

I claim:-

1. Process of producing fine filaments which comprises dissolving cellulose acetate in a mixture 15 of liquids which is a solvent for the cellulose acetate and which consists substantially of methylene chloride and alcohol, extruding the solution through normal apertures into an evaporative atmosphere, the denier of the filaments being regulated by correlating the winding speeds with the concentration of the solvent and non-solvent constituents in the spinning solution.

2. Process of producing filaments of fine denier which comprises extruding a solution of cellulose acetate in a liquid solvent mixture which consists substantially of methylene chloride and alcohol through normal spinning apertures into an evaporative atmosphere, employing winding speeds of '75 to 160 meters per minute.

ARTHUR EIcHENGRiiN. 

